The Federal government should provide a one-stop portal through which to access all government websites with which the citizen does business, as opposed to those where you're just looking for information. For example, once you log into your personal dashboard, you could go to your Social Security account info, your IRS tax account, your passport file; for government employees your OPM account, your personnel info, your TSP account. Over time local and state accounts (i.e., Fairfax county taxes, VA state taxes and drivers info) could be added. Obviously there'd have to be a high level of security on access--using separate cards like the Treasury Direct people do or some more modern and better system. And everything would have to be encrypted and with an audit trail, with all access tracked.
And, as my Kaiser Permanente health account does, you could use the account to exchange protected email messages with the government offices.